How I can change the date format in an input form?

I want to change the format in an input form, date picker, from dd/mm/yyyy to yyyy/mm/dd . I tried the date-format put is not working. can anyone help me?
[date* dob date-format:dd/mm/yy placeholder “Date of Birth”]

thanks

https://wordpress.org/plugins/contact-form-7-datepicker/